Expression profiles of miRNAs in human embryonic stem cells during hepatocyte differentiation

Exploring the roles of non-coding RNAs in liver regeneration

Liver regeneration (LR) is a complex process encompassing three distinct phases: priming, proliferation phase and restoration, all influenced by various regulatory factors. After liver damage or partial resection, the liver tissue demonstrates remarkable restorative capacity, driven by cellular proliferation and repair mechanisms. The essential roles of non-coding RNAs (ncRNAs), predominantly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNA (circRNA), in regulating LR have been vastly studied. Additionally, the impact of ncRNAs on LR and their abnormal expression profiles during this process have been extensively documented. Mechanistic investigations have revealed that ncRNAs interact with genes involved in proliferation to regulate hepatocyte proliferation, apoptosis and differentiation, along with liver progenitor cell proliferation and migration. Given the significant role of ncRNAs in LR, an in-depth exploration of their involvement in the liver's self-repair capacity can reveal promising therapeutic strategies for LR and liver-related diseases. Moreover, understanding the unique regenerative potential of the adult liver and the mechanisms and regulatory factors of ncRNAs in LR are crucial for improving current treatment strategies and exploring new therapeutic approaches for various liver-related diseases. This review provides a brief overview of the LR process and the ncRNA expression profiles during this process. Furthermore, we also elaborate on the specific molecular mechanisms through which multiple key ncRNAs regulate the LR process. Finally, based on the expression characteristics of ncRNAs and their interactions with proliferation-associated genes, we explore their potential clinical application, such as developing predictive indicators reflecting liver regenerative activity and manipulating LR processes for therapeutic purposes.

Transcriptomic Analysis Reveals the Effects of miR-122 Overexpression in the Liver of Qingyuan Partridge Chickens

The liver of chickens is essential for maintaining physiological activities and homeostasis. This study aims to investigate the specific function and molecular regulatory mechanism of microRNA-122 (miR-122), which is highly expressed in chicken liver. A lentivirus-mediated overexpression vector of miR-122 was constructed and used to infect 12-day-old female Qingyuan Partridge chickens. Transcriptome sequencing analysis was performed to identify differentially expressed genes in the liver. Overexpression of miR-122 resulted in 776 differentially expressed genes (DEGs). Enrichment analyses, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) revealed associations with lipid metabolism, cellular senescence, cell adhesion molecules, and the MAPK signaling pathway. Eight potential target genes of miR-122 (ARHGAP32, CTSD, LBH, PLEKHB2, SEC14L1, SLC2A1, SLC6A14, and SP8) were identified through miRNA target prediction platforms and literature integration. This study provides novel insights into the molecular regulatory mechanisms of miR-122 in chicken liver, highlighting its role in key biological processes and signaling pathways. These discoveries enhance our understanding of miR-122's impact on chicken liver function and offer valuable information for improving chicken production performance and health.

Elucidation of how the Mir-23-27-24 cluster regulates development and aging

MicroRNAs (miRNAs) are pivotal regulators of gene expression and are involved in biological processes spanning from early developmental stages to the intricate process of aging. Extensive research has underscored the fundamental role of miRNAs in orchestrating eukaryotic development, with disruptions in miRNA biogenesis resulting in early lethality. Moreover, perturbations in miRNA function have been implicated in the aging process, particularly in model organisms such as nematodes and flies. miRNAs tend to be clustered in vertebrate genomes, finely modulating an array of biological pathways through clustering within a single transcript. Although extensive research of their developmental roles has been conducted, the potential implications of miRNA clusters in regulating aging remain largely unclear. In this review, we use the Mir-23-27-24 cluster as a paradigm, shedding light on the nuanced physiological functions of miRNA clusters during embryonic development and exploring their potential involvement in the aging process. Moreover, we advocate further research into the intricate interplay among miRNA clusters, particularly the Mir-23-27-24 cluster, in shaping the regulatory landscape of aging.

HSCs-derived exosomes regulate the levels of inflammatory cytokines in HIBECs through miR-122-5p mediated p38 MAPK signaling pathway

PBC is an autoimmune-mediated liver disease, and intrahepatic biliary epithelial cells (IBECs) are the target cells of early damage. Previous studies found that miRNAs and inflammation is closely related to PBC. In this study, we extracted exosomes from serum and human IBECs supernatant, and RNA-sequence analyzed the expression profiles of miRNAs. Elisa measured the levels of inflammatory cytokines. RT- qPCR and western blot detected the levels of miR-122-5p, p38 and p-p38. The results showed that 263 differentially expressed (DE) miRNAs were identified in serum exosomes of PBC patients. The levels of IL-1β, IL-6, IL-12, IL-17 A, IFN-γ, TNF-α and TGF-β1 in peripheral blood of PBC patients were higher than those of normal controls. According to the validation results and previous literature, exosomal miR-122-5p was finally selected as the study object, and correlated with inflammatory factors. In vitro experiments further found that exosomal miR-122-5p may derive from hepatic stellate cells (HSCs), and can be HIBECs intake, and influence HIBECs inflammatory factor levels though p38 MAPK signaling pathways. This may provide a new strategy for the treatment of PBC.

Coronary artery disease patient-derived iPSC-hepatocytes have distinct miRNA profile that may alter lipid metabolism

Metabolic dysfunction, partly driven by altered liver function, predisposes to coronary artery disease (CAD), but the role of liver in vulnerable atherosclerotic plaque development remains unclear. Here we produced hepatocyte-like cells (HLCs) from 27 induced pluripotent stem cell (iPSC) lines derived from 15 study subjects with stable CAD (n = 5), acute CAD (n = 5) or healthy controls (n = 5). We performed a miRNA microarray screening throughout the differentiation, as well as compared iPSC-HLCs miRNA profiles of the patient groups to identify miRNAs involved in the development of CAD. MicroRNA profile changed during differentiation and started to resemble that of the primary human hepatocytes. In the microarray, 35 and 87 miRNAs were statistically significantly deregulated in the acute and stable CAD patients, respectively, compared to controls. Down-regulation of miR-149-5p, -92a-3p and -221-3p, and up-regulation of miR-122-5p was verified in the stable CAD patients when compared to other groups. The predicted targets of deregulated miRNAs were enriched in pathways connected to insulin signalling, inflammation and lipid metabolism. The iPSC-HLCs derived from stable CAD patients with extensive lesions had a distinct genetic miRNA profile possibly linked to metabolic dysfunction, potentially explaining the susceptibility to developing CAD. The iPSC-HLCs from acute CAD patients with only the acute rupture in otherwise healthy coronaries did not present a distinct miRNA profile, suggesting that hepatic miRNAs do not explain susceptibility to plaque rupture.

Mir-122 upregulation and let-7f downregulation combination: The effects on hepatic differentiation of hiPSCs on the PCL-Gel-HA nanofibrous scaffold

Cell therapy and tissue engineering as promising candidates for the liver transplantation dilemma are of special interest. Induced pluripotent stem cells (iPSCs) are one of the best sources in this field, but their differentiation methods to hepatocytes have remained challenging. We transduced human iPSCs (hiPSCs) with miR-122 and off-let-7f (hiPSCs^{miR-122 + off-let-7f} ) to evaluate how they can differentiate hiPSCs to hepatocyte-like cells (HLCs) without any extrinsic growth factor. Additionally, we studied the effect of Poly ɛ-caprolactone-gelatin-hyaluronic acid (PCL-Gel-HA) nanofibrous scaffold as an extracellular matrix (ECM) simulator on differentiation improvement. Definitive endoderm markers (FOXA2 and SOX17), as well as hepatic markers (AFP, Albumin, CK18, HNF4α) expression, were significantly higher in hiPSCs^{miR-122 + off-let-7f} derived HLCs (hiPSCs-HLCs) compared to the control group (miR-scramble transduced hiPSCs: hiPSCs^scramble ). hiPSCs-HLCs indicated hepatocyte morphological characteristics and positive immunostaining for AFP, Albumin and HNF4α. Albumin and urea secretion were significantly higher in hiPSCs-HLCs than hiPSCs^scramble . Comparing these markers in the PCL-Gel-HA group with the tissue culture plate (TCP) group revealed that PCL-Gel-HA could improve differentiation towards HLCs significantly. Regarding our results, these microRNAs can be used to differentiate hiPSCs to the functional hepatocytes for disease modelling, drug screening and cell-based therapy in future studies.

Roles of Non-Coding RNAs in Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is an autoimmune-mediated chronic cholestatic liver disease, fatigue, and skin itching are the most common clinical symptoms. Its main pathological feature is the progressive damage and destruction of bile duct epithelial cells. Non-coding RNA (NcRNA, mainly including microRNA, long non-coding RNA and circular RNA) plays a role in the pathological and biological processes of various diseases, especially autoimmune diseases. Many validated ncRNAs are expected to be biomarkers for the diagnosis or treatment of PBC. This review will elucidate the pathogenesis of PBC and help to identify potential ncRNA biomarkers for PBC.

miR-96-5p targets PTEN to mediate sunitinib resistance in clear cell renal cell carcinoma

A multiple receptor tyrosine kinase inhibitor, sunitinib, is a first-line therapy for clear cell renal cell carcinoma (CCRCC). Unfortunately, it has the major challenges of low initial response rate and resistance after about one year of treatment. Here we evaluated a microRNA (miRNA) and its target responsible for sunitinib resistance. Using miRNA profiling, we identified miR-96-5p upregulation in tumors from sunitinib-resistant CCRCC patients. By bioinformatic analysis, PTEN was selected as a potential target of miR-96-5p, which showed low levels in tumors from sunitinib-resistant CCRCC patients. Furthermore, PTEN and miR-96-5p levels were negatively correlated in a large The Cancer Genome Atlas kidney renal clear cell carcinoma cohort and high miR-96 and low PTEN represented poor prognosis in this cohort. Additionally, four-week sunitinib treatment increased miR-96-5p and decreased PTEN only in tumors from a sunitinib-resistant patient-derived xenograft model. We found a novel miR-96-5p binding site in the PTEN 3′ UTR and confirmed direct repression by luciferase reporter assay. Furthermore, we demonstrated that repression of PTEN by miR-96-5p increased cell proliferation and migration in sunitinib-treated cell lines. These results highlight the direct suppression of PTEN by miR-96-5p and that high miR-96-5p and low PTEN are partially responsible for sunitinib resistance and poor prognosis in CCRCC.

MicroRNA Profile of Human Bone Marrow Mesenchymal Stem Cells during Hepatic Differentiation and Therapy

Background and Aims: MicroRNAs (miRNAs) play important roles in hepatocyte differentiation from human bone marrow mesenchymal stem cells (hBMSCs) and the therapeutic application in vivo. However, the mechanisms of miRNA regulation are still unknown. This study aimed to profile the miRNA basis for improving the function of hBMSC-differentiated hepatocyte-like cells (hBMSC-Heps). Methods: Characteristic miRNAs of hBMSC-Heps were identified by transcriptome sequencing and validated by quantitative real-time polymerase chain reaction (qRT-PCR). An in vivo hBMSC transplantation model was used to assess the regulatory effects of miRNAs on liver regeneration during hBMSC therapy in pigs with fulminant hepatic failure (FHF). The biological functions of significant miRNA molecules were confirmed by transfection of miRNA activators or inhibitors into hBMSCs during hepatogenic differentiation. Results: The transcriptome of hBMSC-Heps showed characteristics distinct from those of undifferentiated hBMSCs. A total of 77 miRNAs were significantly differentially expressed in hBMSC-Heps at day 10 and day 20 after hBMSC differentiation that were directly related to the functions of hepatocytes. Among the top 10 significantly differentially expressed and the top 10 most abundant miRNAs, nine miRNAs that exhibited a pattern of gradual change were chosen for further analysis. The expression of nine miRNAs was confirmed by qRT-PCR in vitro and showed the same changing trends in vivo in an hBMSC transplantation model in pigs. Functional experiments with these miRNAs showed that activators of hsa-miR-26b-5p and hsa-miR-148a-3p and an inhibitor of hsa-miR-423-3p were sufficient to improve the differentiation of hBMSCs into hepatocyte-like cells. Conclusions: Transcriptome profiles of miRNA revealed the basis of the differentiation and development of hBMSC-Heps. Manipulation of three miRNAs (hsa-miR-26b-5p, hsa-miR-148a-3p and hsa-miR-423-3p) significantly improved hepatocyte generation and liver regeneration, indicating the potential of these miRNAs for future clinical applications.

Hypoxia-Induced miR-210 Overexpression Promotes the Differentiation of Human-Induced Pluripotent Stem Cells to Hepatocyte-Like Cells on Random Nanofiber Poly-L-Lactic Acid/Poly (ε-Caprolactone) Scaffolds

An alternative treatment to liver transplantation includes the use of differentiated stem cells. Hypoxia has been shown to endow human-induced pluripotent stem cells (hiPSCs) with enhanced hepatic differentiation. We have investigated a new strategy for hepatocyte differentiation from hiPSCs using a three-step differentiation protocol with lentiviral overexpression of hypoxia-microRNA-210 of cells grown on a hybrid scaffold. We analyzed the transduction of the miR-210 lentiviral and definitive endoderm and pluripotency gene markers, including SRY-box 17 (SOX17), forkhead box A2 (FOXA2), and octamer-binding transcription factor 4 (OCT-4) by Real-Time PCR and fluorescent microscope. The scanning electron microscopy (SEM) examined the 3D cell morphological changes. Immunocytochemistry staining was used together with assays for aspartate aminotransferase, alanine aminotransferase, and urea secretion to analyze hepatocyte biomarkers and functional markers consisting of α-fetoprotein (AFP), low-density lipoprotein (LDL) uptake, fat accumulation, and glycogen. The flow cytometry analyzed the generation of reactive oxygen species (ROS). Compared to cells transfected with the blank lentiviral vectors as a control, overexpressing miR-210 was at higher levels in hiPSCs. The expression of endodermal genes and glycogen synthesis significantly increased in the differentiated lentiviral miR-210 cells without any differences regarding lipid storage level. Additionally, cells containing miR-210 showed a greater expression of ALB, LDL, AST, ALT, urea, and insignificant lower AFP and ROS levels after 18 days. However, SEM showed no significant differences between cells under the differentiation process and controls. In conclusion, the differentiation of hiPSCs to hepatocyte-like cells under hypoxia miR-210 may be a suitable method for cell therapy and regenerative medicine.

miR-27b antagonizes BMP signaling in early differentiation of human induced pluripotent stem cells

Human induced pluripotent stem (hiPS) cells are feasible materials for studying the biological mechanisms underlying human embryogenesis. In early embryogenesis, definitive endoderm and mesoderm are differentiated from their common precursor, mesendoderm. Bone morphogenetic protein (BMP) signaling is responsible for regulating mesendoderm and mesoderm formation. Micro RNAs (miRNAs), short non-coding RNAs, broadly regulate biological processes via post-transcriptional repression. The expression of miR-27b, which is enriched in somatic cells, has been reported to increase through definitive endoderm and hepatic differentiation, but little is known about how miR-27b acts during early differentiation. Here, we used miR-27b-inducible hiPS cells to investigate the roles of miR-27b in the undifferentiated and early-differentiated stages. In undifferentiated hiPS cells, miR-27b suppressed the expression of pluripotency markers [alkaline phosphatase (AP) and nanog homeobox (NANOG)] and cell proliferation. Once differentiation began, miR-27b expression repressed phosphorylated SMAD1/5, the mediators of the BMP signaling, throughout definitive endoderm differentiation. Consistent with the above findings, miR-27b overexpression downregulated BMP-induced mesendodermal marker genes [Brachyury, mix paired-like homeobox 1 (MIXL1) and eomesodermin (EOMES)], suggesting that miR-27b had an inhibitory effect on early differentiation. Collectively, our findings revealed a novel antagonistic role of miR-27b in the BMP signaling pathway in the early differentiation of hiPS cells.

MiR-375: A novel multifunctional regulator

MiR-375, a primitively described beta cell-specific miRNA, is confirmed to function as multi-functional regulator in diverse typical cellular pathways according to the follow-up researches. Based on the existing studies, miR-375 can regulate many functional genes and ectopic expressions of miR-375 are usually associated with pathological changes, and its expression regulation mechanism is mainly related to promoter methylation or circRNA. In this review, the regulatory functions of miR-375 in immunity, such as its relevance with macrophages, T helper cells and autoimmune diseases were briefly discussed. Also, the functions of miR-375 involved in inflammation, development and virus replication were reviewed. Finally, the mechanisms and application prospects of miR-375 in cancers were analyzed. Studies show that the application of miR-375 as therapeutic target and biomarker has a broad developing space in future. We hope this paper can provide reference for its further study.

From Liver Cirrhosis to Cancer: The Role of Micro-RNAs in Hepatocarcinogenesis

In almost all cases, hepatocellular carcinoma (HCC) develops as the endpoint of a sequence that starts with chronic liver injury, progresses to liver cirrhosis, and finally, over years and decades, results in liver cancer. Recently, the role of non-coding RNA such as microRNA (miRNA) has been demonstrated in the context of chronic liver diseases and HCC. Moreover, data from a phase II trial suggested a potential role of microRNAs as therapeutics in hepatitis-C-virus infection, representing a significant risk factor for development of liver cirrhosis and HCC. Despite progress in the clinical management of chronic liver diseases, pharmacological treatment options for patients with liver cirrhosis and/or advanced HCC are still limited. With their potential to regulate whole networks of genes, miRNA might be used as novel therapeutics in these patients but could also serve as biomarkers for improved patient stratification. In this review, we discuss available data on the role of miRNA in the transition from liver cirrhosis to HCC. We highlight opportunities for clinical translation and discuss open issues applicable to future developments.

Research Trends in the Efficacy of Stem Cell Therapy for Hepatic Diseases Based on MicroRNA Profiling

Liver diseases, despite the organ’s high regenerative capacity, are caused by several environmental factors and persistent injuries. Their optimal treatment is a liver transplantation. However, this option is limited by donor shortages and immune response issues. Therefore, many researchers have been interested in identifying the therapeutic potential in treating irreversible liver damage based on stem cells and developing suitable therapeutic agents. Mesenchymal stem cells (MSCs), which are representative multipotent stem cells, are known to be highly potential stem cell therapy compared to other stem cells in the clinical trial worldwide. MSCs have therapeutic potentials for several hepatic diseases such as anti-fibrosis, proliferation of hepatocytes injured, anti-inflammation, autophagic mechanism, and inactivation of hepatic stellate cells. There are much data regarding clinical treatments, however, the data for examining the efficacy of stem cell treatment and the correlation between the stem cell engraftment and the efficacy in liver diseases is limited due to the lack of monitoring system for treatment effectiveness. Therefore, this paper introduces the characteristics of microRNAs (miRNAs) and liver disease-specific miRNA profiles, and the possibility of a biomarker that miRNA can monitor stem cell treatment efficacy by comparing miRNAs changed in liver diseases following stem cell treatment. Additionally, we also discuss the miRNA profiling in liver diseases when treated with stem cell therapy and suggest the candidate miRNAs that can be used as a biomarker that can monitor treatment efficacy in liver diseases based on MSCs therapy.

Oligodendrocyte Intrinsic miR-27a Controls Myelination and Remyelination

Remyelination requires the generation of new oligodendrocytes (OLs), which are derived from oligodendrocyte progenitor cells (OPCs). Maturation of OPCs into OLs is a multi-step process. Here, we describe a microRNA expressed by OLs, miR-27a, as a regulator of OL development and survival. Increased levels of miR-27a were found in OPCs associated with multiple sclerosis (MS) lesions and in animal models of demyelination. Increased levels of miR-27a led to inhibition of OPC proliferation by cell-cycle arrest, as well as impaired differentiation of human OPCs (hOPCs) and myelination by dysregulating the Wnt-β-catenin signaling pathway. In vivo administration of miR-27a led to suppression of myelinogenic signals, leading to loss of endogenous myelination and remyelination. Our findings provide evidence supporting a critical role for a steady-state level of OL-specific miR-27a in supporting multiple steps in the complex process of OPC maturation and remyelination.

Role of B Cell Lymphoma 2 in the Regulation of Liver Fibrosis in miR-122 Knockout Mice

MicroRNA-122 (miR-122) has been identified as a marker of various liver injuries, including hepatitis- virus-infection-, alcoholic-, and non-alcoholic steatohepatitis (NASH)-induced liver fibrosis. Here, we report that the extracellular miR-122 from hepatic cells can be delivered to hepatic stellate cells (HSCs) to modulate their proliferation and gene expression. Our published Argonaute crosslinking immunoprecipitation (Ago-CLIP) data identified several pro-fibrotic genes, including Ctgf, as miR-122 targets in mice livers. However, treating Ctgf as a therapeutic target failed to rescue the fibrosis developed in the miR-122 knockout livers. Alternatively, we compared the published datasets of human cirrhotic livers and miR-122 KO livers, which revealed upregulation of BCL2, suggesting its potential role in regulating fibrosis. Notably, ectopic miR-122 expression inhibited BCL2 expression in human HSC (LX-2) cells). Publicly available ChIP-seq data in human hepatocellular cancer (HepG2) cells and mice livers suggested miR-122 could regulate BCL2 expression indirectly through c-MYC, which was confirmed by siRNA-mediated depletion of c-MYC in Hepatocellular Carcinoma (HCC) cell lines. Importantly, Venetoclax, a potent BCL2 inhibitor approved for the treatment of leukemia, showed promising anti-fibrotic effects in miR-122 knockout mice. Collectively, our data demonstrate that miR-122 suppresses liver fibrosis and implicates anti-fibrotic potential of Venetoclax.

Different approaches for transformation of mesenchymal stem cells into hepatocyte-like cells

Due to the prominent role of the liver in the body and detoxification, its functionality can be affected in an irreversible manner by diseases. This phenomenon renders the liver to stop working, leading to morbidity and mortality. Therefore, liver transplantation is the only way to tackle this issue.In order to compensate for the lack of adequate healthy liver tissue for transplantation, therapeutic approaches such as hepatocyte transplantation have been proposed as an alternative. Recognizing the fact that mesenchymal stem cells are adult stem cells with the capacity to differentiate into several cell types, different methods have been invented to produce hepatocyte-like cells from mesenchymal stem cells. They can be divided into three main categories, such as addition of cytokines and growth factors, genetic modifications, and adjustment of microenvironment as well as physical parameters.In this review, we attempted to introduce diverse efficient methods for differentiating mesenchymal stem cells and their capability for transformation into hepatocyte-like cells.

MicroRNA-124a inhibits endoderm lineage commitment by targeting Sox17 and Gata6 in mouse embryonic stem cells

The role of microRNAs (miRNAs) during mouse early development, especially in endoderm germ layer formation, is largely unknown. Here, via miRNA profiling during endoderm differentiation, we discovered that miR‐124a negatively regulates endoderm lineage commitment in mouse embryonic stem cells (mESCs). To further investigate the functional role of miR‐124a in early stages of differentiation, transfection of embryoid bodies with miR‐124a mimic was performed. We showed that overexpression of miR‐124a inhibits endoderm differentiation in vitro through targeting the 3′‐untranslated region (UTR) of Sox17 and Gata6, revealing the existence of interplay between miR‐124a and the Sox17/Gata6 transcription factors in hepato‐specific gene regulation. In addition, we presented a feasible in vivo system that utilizes teratoma and gene expression profiling from microarray to quantitatively evaluate the functional role of miRNA in lineage specification. We demonstrated that ectopic expression of miR‐124a in teratomas by intratumor delivery of miR‐124a mimic and Atelocollagen, significantly suppressed endoderm and mesoderm lineage differentiation while augmenting the differentiation into ectoderm lineage. Collectively, our findings suggest that miR‐124a plays a significant role in mESCs lineage commitment.

Overexpression of microRNA-375 and microRNA-122 promotes the differentiation of human induced pluripotent stem cells into hepatocyte-like cells

MicroRNAs (miRNAs) are involved in the regulation of gene expression. In this study, we evaluated the use of overexpression of microRNA-375 (miR-375) and miR-122 in differentiating the Human Induced Pluripotent Stem Cells (hiPSCs) into functional hepatocyte-like cells (HLCs) without growth factors. We also compared the differentiation by miRNAs versus growth factors. HiPSCs were divided into two main groups: 1- HiPSCs were induced using lentiviral overexpression of miR-375 to differentiate into definitive endoderm (DE) cells in seven days. Then lentiviral overexpression of miR-122 was applied to differentiate DE cells into HLCs in additional 14 days. 2- HiPSCs were differentiated into HLCs using growth factors in 21 days. DE and hepatocyte markers were investigated by qRT-PCR, immunofluorescence, secretion analysis and LDL uptake assay. In the produced cells of both groups: the expression levels of DE markers (FOXA2 and SOX17) and hepatocyte markers (albumin, CK18, and HNF4a) in comparison with the undifferentiated hiPSCs increased significantly in seven and 21 days respectively. The albumin and urea secretion and LDL uptake were also detected. These results weren't significantly different between two groups. Therefore, we demonstrated that the over expression of miR-375 and then miR-122 could differentiate hiPSCs into functional HLCs without growth factors for developing cell-based therapies.

Insight into miRNAs related with glucometabolic disorder

A microRNA (miRNA) is a single-stranded, small and non-coding RNA molecule that contains 20-25 nucleotides. More than 2000 miRNAs have been identified in human genes since the first miRNA was discovered in Caenorhabditis elegans in the early 1990s. miRNAs play a crucial role in various biological processes by regulating gene expression through post-transcriptional mechanisms. The alterations of their levels are associated with various diseases, such as glucometabolic disorder and lipid metabolism disorder. In recent years, miRNAs have been proved to be involved in regulating the functions of pancreatic β-cells, insulin resistance and other biological behaviors related to glucometabolic disorder and the pathogenesis of diabetes mellitus (DM). This review summarized specific miRNAs, including miRNA-375 (miR-375), miRNA-155 (miR-155), miRNA-21 (miR-21), miRNA-33 (miR-33), the let-7 family and some other miRNAs related to glucometabolic regulation, introduced the obstacles and challenges in miRNA therapy, and discussed the prospect of new treatment methods for glucometabolic disorder.

Inositol-Requiring Enzyme 1 Alpha Endoribonuclease Specific Inhibitor STF-083010 Alleviates Carbon Tetrachloride Induced Liver Injury and Liver Fibrosis in Mice

Accumulating data demonstrated that hepatic endoplasmic reticulum (ER) stress was involved in the pathogenesis of liver fibrosis. Long-term chronic hepatocyte death contributed to liver fibrosis initiation and progression. Previous researches reported that ER stress sensor inositol-requiring enzyme 1 alpha (IRE1α) was first activated in the process of liver fibrosis. STF-083010 was an IRE1α RNase specific inhibitor. This study aimed to explore the effects of STF-083010 on carbon tetrachloride (CCl₄)-induced liver injury and subsequent liver fibrosis. Mice were intraperitoneally (i.p.) injected with CCl₄ (0.15 ml/kg) for 8 weeks. In STF-083010+CCl₄ group, mice were injected with STF-083010 (30 mg/kg, i.p.), twice a week, beginning from the 6th week after CCl₄ injection. CCl₄ treatment markedly enhanced the levels of serum ALT, TBIL, DBIL and TBA, and STF-083010 had obviously extenuated CCl₄-induced exaltation of ALT, DBIL, and TBA levels. CCl₄-induced hepatic hydroxyproline and collagen I, major indicators of liver fibrosis, were alleviated by STF-083010. Additionally, CCl₄-induced α-smooth muscle actin, a marker for hepatic stellate cells activation, was obviously attenuated in STF-083010-treated mice. Moreover, CCl₄-induced upregulation of inflammatory cytokines was suppressed by STF-083010. Mechanistic exploration found that hepatic miR-122 was downregulated in CCl₄-treated mice. Hepatic MCP1, CTGF, P4HA1, Col1α1, and Mmp9, target genes of miR-122, were upregulated in CCl₄-treated mice. Interestingly, STF-083010 reversed CCl₄-induced hepatic miR-122 downregulation. Correspondingly, STF-083010 inhibited CCl₄-induced upregulation of miR-122 target genes. This study provides partial evidence that STF-083010 alleviated CCl₄-induced liver injury and thus protected against liver fibrosis associated with hepatic miR-122.

Noncoding RNA Transcripts during Differentiation of Induced Pluripotent Stem Cells into Hepatocytes

Recent advances in the stem cell field allow to obtain many human tissues in vitro. However, hepatic differentiation of induced pluripotent stem cells (iPSCs) still remains challenging. Hepatocyte-like cells (HLCs) obtained after differentiation resemble more fetal liver hepatocytes. MicroRNAs (miRNA) play an important role in the differentiation process. Here, we analysed noncoding RNA profiles from the last stages of differentiation and compare them to hepatocytes. Our results show that HLCs maintain an epithelial character and express miRNA which can block hepatocyte maturation by inhibiting the epithelial-mesenchymal transition (EMT). Additionally, we identified differentially expressed small nucleolar RNAs (snoRNAs) and discovered novel noncoding RNA (ncRNA) genes.

miR-155 and miR-122 Expression of Spermatozoa in Obese Subjects

Obesity is characterized by mild chronic inflammation that is linked with impaired iron homeostasis. Studies in human and murine show that there is a transgenerational epigenetic inheritance via the gametes in obesity; however, there is little information on changes in the expression of microRNAs related to inflammation and iron homeostasis in spermatozoa from obese subjects. The present study investigated the expression of microRNAs related to inflammation (miR-21 y miR-155) and iron nutrition (miR-122 and miR-200b) in plasma, peripheral blood mononuclear cells (PBMC) and spermatozoa from normozoospermic controls (Cn; n = 17; BMI: 24.6 ± 2.0) and obese (Ob; n = 17; BMI: 32.6 ± 4.4) men. To determine the inflammation levels, we measured IL-6, TNF-α, and monocyte chemoattractant protein-1 (MCP1) by Magnetic Luminex^® Assay. mRNA expression of IL6, TNF-α, and hepcidin (HAMP) in PBMC were evaluated by RT-qPCR. The analysis of microRNAs was performed using the Taqman^® assays. The iron content in PBMC, seminal plasma, and spermatozoa was determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). High serum IL6, TNF-α, and MCP1 levels were observed in Ob group (p < 0.05). Gene expression analysis showed an increased abundance relative of TNF-α (p = 0.018), HAMP (p = 0.03), and IL6 (p = 0.02) in PBMC from obese subjects. Also, we observed high levels of serum ferritin (p = 0.03), iron content in seminal plasma (p = 0.04), and spermatozoa (p = 0.002), but lower serum Fe (p = 0.007) in obese subjects. In the Ob group, a high expression of miR-155 (p = 0.02) and miR-21 (p = 0.03) was observed in PBMC and miR-122 (p = 0.03) in plasma. In sperm, both miR-155 (p = 0.004) and miR-122 (p = 0.028) were high in the Ob group. Our results showed that obese subjects have increased expressions of miR-155 and miR-122, two microRNAs that were previously related with inflammation and iron metabolism, respectively, at both the systemic and sperm levels.

Prognostic value of microRNA-9 in cancers: a systematic review and meta-analysis

Recent studies revealed that different microRNA-9 (miR-9) expressions were associated with prognoses of different cancers. We conducted this meta-analysis to evaluate the prognostic value of miR-9. PubMed, Embase, Web of Science, and Cochrane Library (last update by November 30, 2015) were searched for literatures. A total of 17 studies from 16 articles were finally qualified and enrolled in this meta-analysis. Pooled analyses showed that a higher expression of miR-9 might predict poor overall survival (HR: 2.17, 95% CI: 1.39 – 3.41, P < 0.001 (7.23 * 10⁻⁴)), disease-free survival (HR: 5.22, 95% CI: 2.17 – 12.53, P < 0.001 (2.21 * 10⁻⁴)), and recurrence-free survival (HR: 1.57, 95% CI: 1.32 – 1.85, P < 0.001 (1.80*10⁻⁷)) in various carcinomas. However, results of subgroup analyses revealed that down-regulated miR-9 was associated with poor overall survival (HR: 0.45, 95% CI: 0.28 – 0.73, P < 0.001 (1.13*10⁻³)) and progress-free survival (HR: 0.46, 95% CI: 0.34 – 0.62, P < 0.001 (5.03*10⁻⁷)) in ovarian cancer patients. By subgroup analyses we also found that sample collecting time and patients’ origin had little influence on the result of OS. These results indicate that in most cancer types the highly expressed miR-9 is associated with poor survival of patients, whereas the down-regulated miR-9 may predict poor prognosis in patients with ovarian cancer.

Dynamic regulation of EZH2 from HPSc to hepatocyte-like cell fate

Currently, drug metabolization and toxicity studies rely on the use of primary human hepatocytes and hepatoma cell lines, which both have conceivable limitations. Human pluripotent stem cell (hPSC)-derived hepatocyte-like cells (HLCs) are an alternative and valuable source of hepatocytes that can overcome these limitations. EZH2 (enhancer of zeste homolog 2), a transcriptional repressor of the polycomb repressive complex 2 (PRC2), may play an important role in hepatocyte development, but its role during in vitro hPSC-HLC differentiation has not yet been assessed. We here demonstrate dynamic regulation of EZH2 during hepatic differentiation of hPSC. To enhance EZH2 expression, we inducibly overexpressed EZH2 between d0 and d8, demonstrating a significant improvement in definitive endoderm formation, and improved generation of HLCs. Despite induction of EZH2 overexpression until d8, EZH2 transcript and protein levels decreased from d4 onwards, which might be caused by expression of microRNAs predicted to inhibit EZH2 expression. In conclusion, our studies demonstrate that EZH2 plays a role in endoderm formation and hepatocyte differentiation, but its expression is tightly post-transcriptionally regulated during this process.

NEAT1 accelerates the progression of liver fibrosis via regulation of microRNA-122 and Kruppel-like factor 6

Long non-coding RNAs (lncRNAs) have been reported to be involved in many important biological processes including proliferation, apoptosis, differentiation, and survival. Recently, nuclear paraspeckle assembly transcript 1 (NEAT1), a novel lncRNA, serves as a crucial regulator in tumors. However, the biological role of NEAT1 in liver fibrosis is largely unknown. In this study, the role of NEAT1 was explored in primary mouse hepatic stellate cells (HSCs) and carbon tetrachloride (CCl₄)-induced mouse liver fibrosis models. We found that NEAT1 expression was significantly increased in CCl₄-induced mice and activated HSCs. Loss of NEAT1 suppressed liver fibrosis in vivo and in vitro. Conversely, NEAT1 overexpression accelerated HSC activation, including increased cell proliferation and collagen expression. Further studies indicated that the microRNA-122 (miR-122)-Kruppel-like factor 6 (KLF6) axis was involved in the effects of NEAT1 on HSC activation. The effects of NEAT1 on HSC activation were almost blocked down by miR-122 mimics or KLF6 knockdown. Interestingly, both NEAT1 and KLF6 are targets of miR-122. In addition, miR-122 led to a significant reduction in NEAT1 level while NEAT1 overexpression resulted in the suppression of miR-122 expression. Pull-down assay confirmed a direct interaction between miR-122 and NEAT1. NEAT1 contributes to HSC activation via the miR-122-KLF6 axis. In human fibrotic liver samples, increased NEAT1 levels positively correlated with liver fibrosis markers. In conclusion, we disclose a novel NEAT1-miR-122-KLF6 signaling cascade and its implication in liver fibrosis.

KEY MESSAGES

NEAT1 was significantly increased in CCl₄-induced mice and activated HSCs. Loss of NEAT1 suppressed liver fibrosis in vivo and in vitro. KLF6 and miR-122 were required for the effects of NEAT1 on HSC activation. NEAT1 contributes to HSC activation via competitively binding miR-122. We disclose a novel NEAT1-miR-122-KLF6 signaling cascade.

The combination of miR-122 overexpression and Let-7f silencing induces hepatic differentiation of adipose tissue-derived stem cells

Human adipose tissue-derived stem cells (hADSCs) have been considered as a promising source for cell therapy of liver diseases due to their accessibility, abundance, and expression of hepatocyte markers. Currently, the important role of certain microRNAs (miRNAs) has been reported during hepatic differentiation of stem cells. However, the combination effect of miRNAs on hepatic differentiation of these cells needs to be more investigated. The present study seeks to determine whether the combination of miRNAs can enhance hepatic differentiation of hADSCs in the absence of any other stimulation. First, lentiviral transduction was used to overexpress miR-122 and silence d let-7f in hADSCs for up to 21 days. Then, hepatic functionality was evaluated by analyzing specific hepatocyte genes and biochemical markers at different time points of differentiation induction. Stable miR-122 overexpression and let-7f silencing together in hADSCs resulted in increased expression of hepatocyte markers including ALB, AFP, CK18, CK19, and HNF4a. In addition, urea and albumin production, immunocytochemistry, and glycogen staining confirmed that the treated cells differentiated toward hepatocyte-like cells. Therefore, our findings demonstrate the possibility of using microRNAs to induce hADSCs into functional hepatocyte-like cells.

High-throughput sequencing to identify microRNA signatures during hepatic differentiation of human umbilical cord Wharton's jelly-derived mesenchymal stem cells

AIM

MicroRNAs (miRNAs) constitute a class of small non-coding RNAs involved in regulation of cognate mRNAs post-transcriptionally. MicroRNAs have been implicated in regulating the stem cell differentiation process. Limited regulatory miRNAs have been reported to date during hepatic differentiation of stem cells. The present study was designed to identify the signature miRNAs implicated in hepatic differentiation of stem cells using next-generation sequencing methods.

METHODS

We undertook sequencing of miRNAs isolated from three different time points during hepatic differentiation of human umbilical cord Wharton's jelly-derived mesenchymal stem cells (hUC-MSCs) from two biological replicates.

RESULTS

Out of a total known 2588 miRNAs (according to miRBase version 21), 880 miRNAs were identified in our study. A total of 63 significantly expressed miRNAs during hepatic differentiation, with at least 2-fold change and a false discovery rate value <0.05, were considered for further analysis. The putative target genes of significantly downregulated miRNAs during hepatic differentiation appeared to be mostly associated with biological processes that are essential for hepatic differentiation and maintenance of mature hepatic phenotype-like liver development, stem cell differentiation, Wnt receptor signaling pathway, and drug and cholesterol metabolic processes. Putative target genes of significantly upregulated miRNAs are highly enriched in regulating processes that block hepatic differentiation of hUC-MSCs like epithelial-mesenchymal transition, transforming growth factor-β receptor signaling pathway, and stem cell maintenance.

CONCLUSION

The study provides a new insight for investigation of miRNA-regulated pathways during the differentiation process.

Lineage-specific Expression of miR-200 Family in Human Embryonic Stem Cells during In Vitro Differentiation

Although microRNAs have emerged as key regulators in diverse cellular processes, the roles of microRNAs are poorly understood in human embryonic stem cells (hESCs) during differentiation into specialized cell types. In this study, we used a microRNA array with 799 human microRNA probes to examine the expression profiles of microRNAs in hESCs during differentiation into endodermal and mesodermal lineages in vitro. Among the microRNAs analyzed, 7 and 20 microRNAs were enriched in the developmental process of hESCs into mesodermal and endodermal lineages, respectively. In particular, the expression levels of miR-200 family, which is known to regulate the epithelial to mesenchymal transition (EMT), gradually increased in hESCs during differentiation into hepatocytes while they gradually decreased during differentiation into vascular endothelial cells. Downregulation of ZEB1, a direct target of miR-200 family, and E-CADHERIN, a target protein of ZEB1, was observed in hESCs during differentiation into endodermal and mesodermal lineages, respectively. These results indicate that miR-200 family has an important role in determining the cell fate between endodermal and mesodermal lineages from the pluripotent state.

Suppression of the Growth and Invasion of Human Head and Neck Squamous Cell Carcinomas via Regulating STAT3 Signaling and the miR-21/β-catenin Axis with HJC0152

Signal transducer and activator of transcription 3 (STAT3) is involved in the tumor growth and metastasis of human head and neck squamous cell carcinoma (HNSCC) and is therefore a target with therapeutic potential. In this study, we show that HJC0152, a recently developed anticancer agent and a STAT3 signaling inhibitor, exhibits promising antitumor effects against HNSCC both in vitro and in vivo via inactivating STAT3 and downstream miR-21/β-catenin axis. HJC0152 treatment efficiently suppressed HNSCC cell proliferation, arrested the cell cycle at the G₀-G₁ phase, induced apoptosis, and reduced cell invasion in both SCC25 and CAL27 cell lines. Moreover, HJC0152 inhibited nuclear translocation of phosphorylated STAT3 at Tyr705 and decreased VHL/β-catenin signaling activity via regulation of miR-21. Loss of function of VHL remarkably compromised the antitumor effect of HJC0152 in both cell lines. In our SCC25-derived orthotopic mouse models, HJC0152 treatment significantly abrogated STAT3/β-catenin expression in vivo, leading to a global decrease of tumor growth and invasion. With its favorable aqueous solubility and oral bioavailability, HJC0152 holds the potential to be translated into the clinic as a promising therapeutic strategy for patients with HNSCC. Mol Cancer Ther; 16(4); 578-90. ©2017 AACR.

MiRNAs in β-Cell Development, Identity, and Disease

Pancreatic β-cells regulate glucose metabolism by secreting insulin, which in turn stimulates the utilization or storage of the sugar by peripheral tissues. Insulin insufficiency and a prolonged period of insulin resistance are usually the core components of type 2 diabetes (T2D). Although, decreased insulin levels in T2D have long been attributed to a decrease in β-cell function and/or mass, this model has recently been refined with the recognition that a loss of β-cell “identity” and dedifferentiation also contribute to the decline in insulin production. MicroRNAs (miRNAs) are key regulatory molecules that display tissue-specific expression patterns and maintain the differentiated state of somatic cells. During the past few years, great strides have been made in understanding how miRNA circuits impact β-cell identity. Here, we review current knowledge on the role of miRNAs in regulating the acquisition of the β-cell fate during development and in maintaining mature β-cell identity and function during stress situations such as obesity, pregnancy, aging, or diabetes. We also discuss how miRNA function could be harnessed to improve our ability to generate β-cells for replacement therapy for T2D.

Massive rearrangements of cellular MicroRNA signatures are key drivers of hepatocyte dedifferentiation

Hepatocytes are dynamic cells that, upon injury, can alternate between nondividing differentiated and dedifferentiated proliferating states in vivo. However, in two-dimensional cultures, primary human hepatocytes (PHHs) rapidly dedifferentiate, resulting in loss of hepatic functions that significantly limits their usefulness as an in vitro model of liver biology, liver diseases, as well as drug metabolism and toxicity. Thus, understanding the underlying mechanisms and stalling of the dedifferentiation process would be highly beneficial to establish more-accurate and relevant long-term in vitro hepatocyte models. Here, we present comprehensive analyses of whole proteome and transcriptome dynamics during the initiation of dedifferentiation during the first 24 hours of culture. We report that early major rearrangements of the noncoding transcriptome, hallmarked by increased expression of small nucleolar RNAs, long noncoding RNAs, microRNAs (miRNAs), and ribosomal genes, precede most changes in coding genes during dedifferentiation of PHHs, and we speculated that these modulations could drive the hepatic dedifferentiation process. To functionally test this hypothesis, we globally inhibited the miRNA machinery using two established chemically distinct compounds, acriflavine and poly-l-lysine. These inhibition experiments resulted in a significantly impaired miRNA response and, most important, in a pronounced reduction in the down-regulation of hepatic genes with importance for liver function. Thus, we provide strong evidence for the importance of noncoding RNAs, in particular, miRNAs, in hepatic dedifferentiation, which can aid the development of more-efficient differentiation protocols for stem-cell-derived hepatocytes and broaden our understanding of the dynamic properties of hepatocytes with respect to liver regeneration.

CONCLUSION

miRNAs are important drivers of hepatic dedifferentiation, and our results provide valuable information regarding the mechanisms behind liver regeneration and possibilities to inhibit dedifferentiation in vitro. (Hepatology 2016;64:1743-1756).

The role of microRNAs in liver injury at the crossroad between hepatic cell death and regeneration

The liver fulfills critical metabolic functions, such as controlling blood sugar and ammonia levels, and is of central importance for lipid metabolism and detoxification of environmental and chemical agents, including drugs. Liver injuries of different etiology can elicit a spectrum of responses. Some hepatocytes initiate molecular programs resulting in cell death, whereas others undergo cellular divisions to regenerate the damaged organ. Interestingly, recent research indicates that microRNAs serve as very rapid as well as long-term regulators in these processes. In this review, we discuss their importance in liver disease etiology and progression as well as for therapy with particular focus on metabolic and inflammatory conditions. Furthermore, we highlight the central role of microRNAs in controlling hepatocyte differentiation and plasticity, which are required for successful regeneration, but under certain conditions, such as chronic liver insults, can result in the formation of hepatocellular carcinoma.

A decrease in hepatic microRNA-9 expression impairs gluconeogenesis by targeting FOXO1 in obese mice

AIM/HYPOTHESIS

MicroRNA-9 (miR-9) is involved in the regulation of pancreatic beta cell function. However, its role in gluconeogenesis is still unclear. Our objective was to investigate the role of miR-9 in hepatic glucose production (HGP).

METHODS

MiR-9 expression was measured in livers of high-fat diet (HFD) mice and ob/ob mice. The methylation status of the miR-9-3 promoter regions in hepatocytes was determined by the methylation-specific PCR procedure. The binding activity of DNA methyltransferase (DNMT)1, DNMT3a and DNMT3b on the miR-9-3 promoter was detected by chromatin immunoprecipitation (ChIP) and quantitative real-time PCR assays. HGP was evaluated in vitro and in vivo. Glucose tolerance, insulin tolerance and pyruvate tolerance tests were also performed.

RESULTS

Reduced miR-9 expression and hypermethylation of the miR-9-3 promoter were observed in the livers of obese mice. Further study showed that the binding of DNMT1, but not of DNMT3a and DNMT3b, to the miR-9-3 promoter was increased in hepatocytes from ob/ob mice. Knockdown of DNMT1 alleviated the decrease in hepatic miR-9 expression in vivo and in vitro. Overexpression of hepatic miR-9 improved insulin sensitivity in obese mice and inhibited HGP. In addition, deletion of hepatic miR-9 led to an increase in random and fasting blood glucose levels in lean mice. Importantly, silenced forkhead box O1 (FOXO1) expression reversed the gluconeogenesis and glucose production in hepatocytes induced by miR-9 deletion.

CONCLUSIONS/INTERPRETATION

Our observations suggest that the decrease in miR-9 expression contributes to an inappropriately activated gluconeogenesis in obese mice.

MicroRNAs in the Evaluation and Potential Treatment of Liver Diseases

Acute and chronic liver disease continue to result in significant morbidity and mortality of patients, along with increasing burden on their families, society and the health care system. This in part is due to increased incidence of liver disease associated factors such as metabolic syndrome; improved survival of patients with chronic predisposing conditions such as HIV; as well as advances in the field of transplantation and associated care leading to improved survival. The fact that one disease can result in different manifestations and outcomes highlights the need for improved understanding of not just genetic phenomenon predisposing to a condition, but additionally the role of epigenetic and environmental factors leading to the phenotype of the disease. It is not surprising that providers continue to face daily challenges pertaining to diagnostic accuracy, prognostication of disease severity, progression, and response to therapies. A number of these challenges can be addressed by incorporating a personalized approach of management to the current paradigm of care. Recent advances in the fields of molecular biology and genetics have paved the way to more accurate, individualized and precise approach to caring for liver disease. The study of microRNAs and their role in both healthy and diseased livers is one example of such advances. As these small, non-coding RNAs work on fine-tuning of cellular activities and organ function in a dynamic and precise fashion, they provide us a golden opportunity to advance the field of hepatology. The study of microRNAs in liver disease promises tremendous improvement in hepatology and is likely to lay the foundation towards a personalized approach in liver disease.

Enhanced expression of hepatocyte-specific microRNAs in valproic acid mediated hepatic trans-differentiation of human umbilical cord derived mesenchymal stem cells

MicroRNAs (miRNAs) play an important role in the control of cell fate determination during differentiation. In this study, we analyzed the expression pattern of microRNAs (miRNAs) during hepatic trans-differentiation. The protocol employed the use of histone deacetylase inhibitor (HDACI), valproic acid (VPA) to induce hepatic trans-differentiation of human umbilical cord Wharton's jelly derived mesenchymal stem cells (hUC-MSCs). The differentiated hepatocyte like cells (HLCs) from hUC-MSCs shared typical characteristics with mature hepatocytes, including morphology, expression of hepatocyte -specific genes at the molecular and cellular level. Moreover, the functionality of HLCs was confirmed through various liver function tests such as periodic acid-Schiff (PAS) stain for glycogen accumulation, enzyme-linked immunosorbent assay (ELISA) for synthesis of albumin and release of urea. The aim of the present work was to examine the effect of VPA treatment on miRNA expression during hepatic trans-differentiation. The analysis at miRNA level showed that there was a significant increase in expression of miRNAs involved in hepatic differentiation, due to VPA pre-treatment during differentiation. The study, thus demonstrated that improved expression of hepatocyte-specific miRNAs, miR-23b cluster (miR-27b-3p, miR-24-1-5p and miR-23b-3p), miR-30a-5p, miR-26a-5p, miR-148a-3p, miR-192-5p, miR-122-5p due to VPA pre-treatment contributed to a more efficient hepatic trans-differentiation from hUC-MSCs. The putative targets of these upregulated miRNAs were predicted using Bioinformatics analysis. Finally, miR-122-5p, highly upregulated miRNA during hepatic differentiation, was selected for target verification studies. Thus, this study also provides the basis for the function of miR-122-5p during hepatic differentiation of hUC-MSCs.

Function and clinical potential of microRNAs in hepatocellular carcinoma

MicroRNAs (miRNAs) are small non-coding RNAs involved in the initiation and progression of several types of human cancer, including hepatocellular carcinoma (HCC), which is one of the most common types of cancer and the third leading cause of cancer-related mortality worldwide. Mounting evidence has demonstrated that miRNAs play a vital role in HCC, hepatitis, alcoholic liver disease, liver cell development and the metabolic functions of the liver. The aim of the present review was to summarize the most recent findings on the functions of miRNAs in the liver and discuss their potential roles in the diagnosis, prognosis and treatment of HCC.

Changes in microRNA expression during differentiation of embryonic and induced pluripotent stem cells to definitive endoderm

Pluripotent stem cells, including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have the potential to treat type 1 diabetes through cell replacement therapy. However, the protocols used to generate insulin-expressing cells in vitro frequently result in cells which have an immature phenotype and are functionally restricted. MicroRNAs (miRNAs) are now known to be important in cell fate specification, and a unique miRNA signature characterises pancreatic development at the definitive endoderm stage. Several studies have described differences in miRNA expression between ESCs and iPSCs. Here we have used microarray analysis both to identify miRNAs up- or down-regulated upon endoderm formation, and also miRNAs differentially expressed between ESCs and iPSCs. Several miRNAs fulfilling both these criteria were identified, suggesting that differences in the expression of these miRNAs may affect the ability of pluripotent stem cells to differentiate into definitive endoderm. The expression of these miRNAs was validated by qRT-PCR, and the relationship between one of these miRNAs, miR-151a-5p, and its predicted target gene, SOX17, was investigated by luciferase assay, and suggested an interaction between miR-151a-5p and this key transcription factor. In conclusion, these findings demonstrate a unique miRNA expression pattern for definitive endoderm derived from both embryonic and induced pluripotent stem cells.

Anti-fibrotic Role of miR-214 in Thioacetamide-induced Liver Cirrhosis in Rats

An increasing number of studies have focused on the role of microRNAs in liver fibrosis/cirrhosis. miR-214 has recently attracted more attention as a fibrosis-related factor; however, the molecular mechanisms in hepatic fibrogenesis remain largely unknown. Here, we investigate the pathological role of miR-214 during progression of liver cirrhosis in rats. Rats were injected intraperitoneally with thioacetamide at a dose of 100 mg/kg body weight, twice a week. The liver was collected at post first injection weeks 5, 10, 15, and 20. Hepatic expression of miR-214 was analyzed by real-time polymerase chain reaction, in situ hybridization, and laser microdissection. The effects of miR-214 overexpression were investigated by in vitro transfection using fibroblastic MT-9 cells. miR-214 was highly upregulated in the fibrotic area in parallel with the cirrhosis progression. miR-214 overexpression in MT-9 cells under transforming growth factor-β1 stimulation resulted in decreased cell number and increased expression of cleaved caspase 3 and decreased expression of α-smooth muscle actin, suggesting that miR-214 induces apoptosis and inhibits myofibroblast differentiation in fibroblastic cells under stimulation of fibrogenic factors. These data indicate an anti-fibrotic role of miR-214 in chemically induced liver fibrosis/cirrhosis.

Combination treatment with doxorubicin and microRNA-21 inhibitor synergistically augments anticancer activity through upregulation of tumor suppressing genes

Doxorubicin (DOX) is a key chemotherapeutic drug for cancer treatment. The antitumor mechanism of DOX is its action as a topoisomerase II poison by preventing DNA replication. Our study shows that DOX can be involved in epigenetic regulation of gene transcription through downregulation of DNA methyltransferase 1 (DNMT1) then reactivation of DNA methylation-silenced tumor suppressor genes in glioblastoma (GBM). Recent evidence demonstrated that microRNA (miR or miRNA) can mediate expression of genes through post-transcriptional regulation and modulate sensitivity to anticancer drugs. As one of the first miRNAs detected in the human genome, miR-21 has been validated to be overexpressed in GBM. Combination treatment of a chemotherapeutic and miRNA showed synergistically increased anticancer activities which has been proven to be an effective strategy for tumor therapy. In our study, co-treatment of DOX and miR-21 inhibitor (miR-21i) resulted in remarkably increased expression of tumor suppressor genes compared with DOX or the miR-21i treatment alone. Moreover, we demonstrate that combining DOX and miR-21i significantly reduced tumor cell proliferation, invasion and migration in vitro. Our study concludes that combining DOX and miR-21i is a new strategy for the therapy of GBM.

Switching of pyruvate kinase isoform L to M2 promotes metabolic reprogramming in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is an aggressive tumor, with a high mortality rate due to late symptom presentation and frequent tumor recurrences and metastasis. It is also a rapidly growing tumor supported by different metabolic mechanisms; nevertheless, the biological and molecular mechanisms involved in the metabolic reprogramming in HCC are unclear. In this study, we found that pyruvate kinase M2 (PKM2) was frequently over-expressed in human HCCs and its over-expression was associated with aggressive clinicopathological features and poor prognosis of HCC patients. Furthermore, knockdown of PKM2 suppressed aerobic glycolysis and cell proliferation in HCC cell lines in vitro. Importantly, knockdown of PKM2 hampered HCC growth in both subcutaneous injection and orthotopic liver implantation models, and reduced lung metastasis in vivo. Of significance, PKM2 over-expression in human HCCs was associated with a down-regulation of a liver-specific microRNA, miR-122. We further showed that miR-122 interacted with the 3UTR of the PKM2 gene. Re-expression of miR-122 in HCC cell lines reduced PKM2 expression, decreased glucose uptake in vitro, and suppressed HCC tumor growth in vivo. Our clinical data and functional studies have revealed a novel biological mechanism involved in HCC metabolic reprogramming.

MicroRNA-122: a novel hepatocyte-enriched in vitro marker of drug-induced cellular toxicity

Emerging hepatic models for the study of drug-induced toxicity include pluripotent stem cell-derived hepatocyte-like cells (HLCs) and complex hepatocyte-non-parenchymal cellular coculture to mimic the complex multicellular interactions that recapitulate the niche environment in the human liver. However, a specific marker of hepatocyte perturbation, required to discriminate hepatocyte damage from non-specific cellular toxicity contributed by non-hepatocyte cell types or immature differentiated cells is currently lacking, as the cytotoxicity assays routinely used in in vitro toxicology research depend on intracellular molecules which are ubiquitously present in all eukaryotic cell types. In this study, we demonstrate that microRNA-122 (miR-122) detection in cell culture media can be used as a hepatocyte-enriched in vitro marker of drug-induced toxicity in homogeneous cultures of hepatic cells, and a cell-specific marker of toxicity of hepatic cells in heterogeneous cultures such as HLCs generated from various differentiation protocols and pluripotent stem cell lines, where conventional cytotoxicity assays using generic cellular markers may not be appropriate. We show that the sensitivity of the miR-122 cytotoxicity assay is similar to conventional assays that measure lactate dehydrogenase activity and intracellular adenosine triphosphate when applied in hepatic models with high levels of intracellular miR-122, and can be multiplexed with other assays. MiR-122 as a biomarker also has the potential to bridge results in in vitro experiments to in vivo animal models and human samples using the same assay, and to link findings from clinical studies in determining the relevance of in vitro models being developed for the study of drug-induced liver injury.

Promoting the recovery of injured liver with poly (3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) scaffolds loaded with umbilical cord-derived mesenchymal stem cells

Cell-based therapies are major focus of current research for treatment of liver diseases. In this study, mesenchymal stem cells were isolated from human umbilical cord Wharton's jelly (WJ-MSCs). Results confirmed that WJ-MSCs isolated in this study could express the typical MSC-specific markers and be induced to differentiate into adipocytes, osteoblasts, and chondrocytes. They could also be induced to differentiate into hepatocyte-like cells. Poly (3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBVHHx) is a new member of polyhydroxyalkanoate family and biodegradable polyester produced by bacteria. PHBVHHx scaffolds showed much higher cell attachment and viability than the other polymers tested. PHBVHHx scaffolds loaded with WJ-MSCs were transplanted into liver-injured mice. Liver morphology improved after 30 days of transplantation and looked similar to normal liver. Concentrations of serum alanine aminotransferase and total bilirubin were significantly lower, and albumin was significantly higher on days 14 and 30 in the WJ-MSCs+scaffold group than in the carbon tetrachloride (CCl4) group. Hematoxylin-eosin staining showed that liver had similar structure of normal liver lobules and similar size and shape of normal hepatic cells, and Masson staining demonstrated that liver had less blue staining for collagen after 30 days of transplantation. Real-time reverse transcription-polymerase chain reaction (RT-PCR) showed that the expression of the bile duct epithelial cell gene CK-19 in mouse liver is significantly lower on days 14 and 30 in the WJ-MSCs+scaffold group than in the CCl4 group. Real-time RT-PCR, immunocytochemistry, and periodic acid-Schiff staining showed that WJ-MSCs in scaffolds differentiated into hepatocyte-like cells on days 14 and 30 in the WJ-MSCs+scaffold group. Real-time RT-PCR also demonstrated that WJ-MSCs in scaffolds expressed endothelial cell genes Flk-1, vWF, and VE-cadherin on days 14 and 30 in the WJ-MSCs+scaffold group, indicating that WJ-MSCs also differentiated into endothelial-like cells. These results demonstrated that PHBVHHx scaffolds loaded with WJ-MSCs significantly promoted the recovery of injured liver and could be further studied for liver tissue engineering.

miR-27 negatively regulates pluripotency-associated genes in human embryonal carcinoma cells

Human embryonic stem cells and human embryonal carcinoma cells have been studied extensively with respect to the transcription factors (OCT4, SOX2 and NANOG), epigenetic modulators and associated signalling pathways that either promote self-renewal or induce differentiation in these cells. The ACTIVIN/NODAL axis (SMAD2/3) of the TGFß signalling pathway coupled with FGF signalling maintains self-renewal in these cells, whilst the BMP (SMAD1,5,8) axis promotes differentiation. Here we show that miR-27, a somatic-enriched miRNA, is activated upon RNAi-mediated suppression of OCT4 function in human embryonic stem cells. We further demonstrate that miR-27 negatively regulates the expression of the pluripotency-associated ACTIVIN/NODAL axis (SMAD2/3) of the TGFß signalling pathway by targeting ACVR2A, TGFßR1 and SMAD2. Additionally, we have identified a number of pluripotency-associated genes such as NANOG, LIN28, POLR3G and NR5A2 as novel miR-27 targets. Transcriptome analysis revealed that miR-27 over-expression in human embryonal carcinoma cells leads indeed to a significant up-regulation of genes involved in developmental pathways such as TGFß- and WNT-signalling.

miR-21 in ischemia/reperfusion injury: a double-edged sword?

MicroRNAs (miRNAs or miRs) are endogenous, small RNA molecules that suppress expression of targeted mRNA. miR-21, one of the most extensively studied miRNAs, is importantly involved in divergent pathophysiological processes relating to ischemia/reperfusion (I/R) injury, such as inflammation and angiogenesis. The role of miR-21 in renal I/R is complex, with both protective and pathological pathways being regulated by miR-21. Preconditioning-induced upregulation of miR-21 contributes to the protection against subsequent renal I/R injury through the targeting of genes such as the proapoptotic gene programmed cell death 4 and interactions between miR-21 and hypoxia-inducible factor. Conversely, long-term elevation of miR-21 may be detrimental to the organ by promoting the development of renal interstitial fibrosis following I/R injury. miR-21 is importantly involved in several pathophysiological processes related to I/R injury including inflammation and angiogenesis as well as the biology of stem cells that could be used to treat I/R injury; however, the effect of miR-21 on these processes in renal I/R injury remains to be studied.

MicroRNAs: the fine modulators of liver development and function

MicroRNAs are a class of small non-coding RNAs involved in the transcriptional and post-transcriptional regulation of gene expression. The function of miRNAs in liver disease including hepatocellular carcinoma (HCC), hepatitis, and alcoholic liver disease, have been widely studied and extensively reviewed. Increasing evidence demonstrates that miRNAs also play a critical role in normal liver development and in the fine-tuning of fundamental biological liver processes. In this review, we highlight the most recent findings on the role of miRNAs in liver specification and differentiation, liver cell development, as well as in the many metabolic functions of the liver, including glucose, lipid, iron and drug metabolism. These findings demonstrate an important role of miRNAs in normal liver development and function. Further researches will be needed to fully understand how miRNAs regulate liver generation and metabolic function, which should then lead to greater insights in liver biology and perhaps open up the possibility to correct errors that cause liver diseases or metabolic disorders.